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#include

#include

#include

typedef unsigned char BYTE;

#define RGB 3.0

#define MAX 255.0

struct BitMap

{

short Type;

long Size;

short Reserve1;

short Reserve2;

long Offset;

long FileSize;

long Width;

long Height;

short ClrPlanes;

short BitsPerPix;

long Compression;

long ImSize;

long XPixPerMeter;

long YPixPerMeter;

long ClrTBClr;

long ImpClr;

} Header;

typedef struct

{

BYTE Blue;

BYTE Green;

BYTE Red;

} __attribute__((__packed__))

RGBTRIPLE;

int main(int argc, char **argv) {

FILE *inptr, *outptr;

float threshold;

threshold = atoi(argv[2]);

if(argc < 3) {

printf("Usage : ./a.out threshold\n");

exit(0);

}

else inptr = fopen(argv[1], "rb");

outptr = fopen ("out.bmp", "wb");

memset(&Header, 0, sizeof(Header));

fread(&Header.Type, 2, 1, inptr);

fwrite(&Header.Type, 2, 1, outptr);

fread(&Header.Size, 4, 1, inptr);

fwrite(&Header.Size, 4, 1, outptr);

fread(&Header.Reserve1, 2, 1, inptr);

fwrite(&Header.Reserve1, 2, 1, outptr);

fread(&Header.Reserve2, 2, 1, inptr);

fwrite(&Header.Reserve2, 2, 1, outptr);

fread(&Header.Offset, 4, 1, inptr);

fwrite(&Header.Offset, 4, 1, outptr);

fread(&Header.FileSize, 4, 1, inptr);

fwrite(&Header.FileSize, 4, 1, outptr);

fread(&Header.Width, 4, 1, inptr);

fwrite(&Header.Width, 4, 1, outptr);

fread(&Header.Height, 4, 1, inptr);

fwrite(&Header.Height, 4, 1, outptr);

fread(&Header.ClrPlanes, 2, 1, inptr);

fwrite(&Header.ClrPlanes, 2, 1, outptr);

fread(&Header.BitsPerPix, 2, 1, inptr);

fwrite(&Header.BitsPerPix, 2, 1, outptr);

fread(&Header.Compression, 4, 1, inptr);

fwrite(&Header.Compression, 4, 1, outptr);

fread(&Header.ImSize, 4, 1, inptr);

fwrite(&Header.ImSize, 4, 1, outptr);

fread(&Header.XPixPerMeter, 4, 1, inptr);

fwrite(&Header.XPixPerMeter, 4, 1, outptr);

fread(&Header.YPixPerMeter, 4, 1, inptr);

fwrite(&Header.YPixPerMeter, 4, 1, outptr);

fread(&Header.ClrTBClr, 4, 1, inptr);

fwrite(&Header.ClrTBClr, 4, 1, outptr);

fread(&Header.ImpClr, 4, 1, inptr);

fwrite(&Header.ImpClr, 4, 1, outptr);

// iterate over infile's scanlines

int i,j;

if (Header.Compression!=24) {

printf("Error: This program only deals with 24 compressed bmp file\n");

return 1;

}

if (threshold <0 || threshold >1.0) {

printf("Error: Threshold value is not valid\n");

return 1;

}

else for (i=0; i

{

// iterate over pixels in scanline

for (j=0; j

{

// temporary storage

RGBTRIPLE triple, tripleout;

int sum = 0;

// read RGB triple from infile

fread(&triple, sizeof(RGBTRIPLE), 1, inptr);

sum = triple.Red+triple.Green+triple.Blue;

float ratio = sum/(RGB*MAX);

printf("(%d, %d, %d)\n", triple.Red, triple.Green, triple.Blue);

// prints rgb values for each pixel (used to check if the colours were right)

printf("ratio is: %f\n", ratio);

// gives the ratio

if (ratio

tripleout.Red = 0;

tripleout.Green = 0;

tripleout.Blue = 0;

}

// this part needs to be done

else {

tripleout.Red = 255;

tripleout.Green = 255;

tripleout.Blue = 255;

}

// write RGB triple to outfile

fwrite(&tripleout, sizeof(RGBTRIPLE), 1, outptr);

}

}

fclose(inptr);

fclose(outptr);

return 0;

}

/* To use compile: gcc -Wall -o check2 check2.c

After compiling

./check filename.bmp thresholdvalue

*/